Many systems and methods are currently available for replacing lost teeth. These systems and methods comprise the following basic steps. First, an implant is threaded into a cavity formed in the patient's jaw at the location of a lost tooth. The implant is then allowed to osseointegrate with the jaw bone. A technician will then fabricate a prosthetic tooth on a permanent abutment member. The permanent abutment member is then attached to the implant to mount the prosthetic tooth at its appropriate location. In this context, the permanent abutment member forms the structural attachment between the prosthetic tooth and the implant, and the prosthetic tooth functionally and aesthetically replaces the exposed portion of the lost tooth.
It should be clear that this basic process can be employed when replacing a plurality of teeth as well as when replacing a single tooth. In the following discussion, the present invention is described in the context of replacing a single tooth; but one of ordinary skill in the art will recognize that the principles of the present invention are equally applicable to the replacement of more than one tooth at a time.
The step of fabricating the prosthetic tooth varies with the particular patient but requires that the position of the implant be captured so that the resulting prosthesis performs as required both functionally and aesthetically. If the position of the implant is not accurately captured, the resulting prosthesis may not function properly and may not look natural when attached to the implant.
The prosthesis fabrication process comprises the steps of taking an impression of the area of the lost tooth and, with the impression, forming a model of the area of the lost tooth. The process of taking the impression comprises the steps of attaching an impression coping to the implant, injecting hardenable impression material into the area surrounding the impression coping, and, when the impression material hardens, removing the impression material with the impression coping encased therein. To fabricate the model, an analog of the implant is then attached to the impression coping encased in the impression. Hardenable model material is then placed around the implant analog and allowed to harden. The model, with the implant analog buried therein, is then removed from the impression.
The position of the implant analog in the model should, and in most systems will, reflect the position of the implant in the mouth; that is, the model will contain surfaces corresponding to the surfaces of the teeth and soft tissue, with these model surfaces being accurately located relative to the implant analog. If the model accurately reflects the position of the implant in the mouth, a technician can accurately fabricate the prosthetic tooth in a laboratory setting.
While most currently available systems for replacing lost teeth allow the fabrication of a model that accurately reflects the position of the implant in the mouth, these systems each have drawbacks that, in general, result in the process of replacing lost teeth being fairly complicated and expensive.
To the Applicant's knowledge, all of the currently available systems and methods employ metal parts down to the implant during the process of taking the impression. Such metal parts are precision machined and thus relatively expensive. Although metal parts are in theory reusable, they must be sterilized between each use. And even if sterilized, these metal parts are often difficult to clean completely. Accordingly, in practice these parts are often discarded after being used once to eliminate the possibility of cross-contamination.
The use of metal parts also increases the complexity of previously available systems or methods for replacing lost teeth. More specifically, during the process of taking an impression and subsequently creating a model from that impression, it is necessary to temporarily join two components together (i.e., the impression coping is joined to the implant and the implant analog is joined to the impression coping). Using currently available systems, whenever two metal components are temporarily joined together, one of two methods must be used: (a) one of the components must be directly threaded onto the other; or (b) one of the components is internally threaded, the other component is unthreaded, and a separate screw engages the threaded component to attach the unthreaded component to the threaded component.
In the case where both of the components are threaded, one component is usually fixed and the other is rotated relative to the fixed component. For one component to be directly threaded onto another, one of these components must be freely rotatable relative to the other. For example, in certain systems, healing abutments are provided with a threaded post extending therefrom. To attach the healing abutment to the implant, the healing abutment is rotated relative to the implant such that the threaded post formed thereon is received within the threaded cavity defined by the implant.
Rotating one component relative to the other is not possible in many situations; for example, this is not possible when one of the components is an implant fixed within the mouth and the other is an impression coping fixed within an impression.
Accordingly, with previously available systems, the various components employed are attached to each other using threaded screws during the process of taking an impression and making a model therefrom. A screw is used to securely attach the impression coping to the implant while the impression material is injected around the impression coping. And a screw is also used to attach the implant analog to the impression coping during the process of making the model from the impression.
The use of screws to attach the impression coping onto the implant increases the complexity of the process of taking the impression. The dentist must thread the screw into the implant before the impression is taken and remove the screw from the implant to remove the impression from the mouth.
Another important drawback of prior art systems and methods of replacing teeth is that these systems commonly employ 20-30 components each having a specific purpose. Many of these components work only with a specific subset of other components.
In any case, all of the components of a given system must kept in inventory. And accurate records be kept to ensure that the oral surgeon, dentist, and laboratory technician all have the right parts at the right time. Further, because these components are small and many differ only in size, the difference between one component and another incompatible component may not be obvious to the naked eye, possibly resulting in confusion among various similar looking parts.
The fact that certain components work only with certain other components reduces the flexibility of the system. For example, in certain prior art systems, the permanent abutment member must be selected prior to the process of making the impression because a particular impression coping must be used for the selected permanent abutment. If, subsequently, the dentist or laboratory technician determines that another type of permanent abutment is more appropriate, a new impression with a different impression coping must be made.